A liquid state detection sensor that, for example, is provided in a fuel tank and detects a remaining fuel amount in the fuel tank is generally known.
As this kind of fuel state detection sensor, for example, the technology recited in Japanese Patent Application Laid-Open (JP-A) No. 2010-25782 has been proposed. For this technology, a sensor is proposed in which a first detection electrode, which is in a measured liquid, a second detection electrode, which measures a liquid level of the measured liquid, and a third detection electrode, which is permanently outside the measured liquid, are provided, and operations of charging a capacitor for a duration proportional to the length of a region in which the second detection electrode is immersed in the measured liquid and discharging the capacitor for a duration proportional to the length of a region in which the second detection electrode is outside the measured liquid are repeated.